The Impact of Bariatric Surgery on NASH
The Impact of Bariatric Surgery on NASH
Currently, bariatric surgery is accepted as a treatment for obesity based on a combination of BMI levels and the presence of features of the metabolic syndrome. All techniques for performing bariatric surgery may be used in subjects with BMI ≥ 35 kg/m and any feature of the metabolic syndrome, or in subjects with BMI ≥ 40 kg/m independent of the presence of associated diseases. Recently, the U.S. Food and Drug Administration (FDA) approved the use of laparoscopic adjustable gastric banding for use in individuals with a BMI ≥ 30 kg/m and a feature of the metabolic syndrome. Nevertheless, bariatric surgery is not an option for every severely obese individual. Appropriate candidates are those who are willing to make significant changes in eating habits and lifestyle, and adhere to long-term follow-up care.
A few different bariatric surgery techniques are available and the choice of technique is currently based mainly on patient and surgeon preference, while taking into account the available evidence regarding the risks and benefits of each procedure. All techniques can be done using the laparoscopic approach. One of the most common and standard techniques available is adjustable gastric banding (AGB) (Fig. 1), in which an inflatable and adjustable silicone band is placed around the upper stomach, close to the gastroesophageal junction, to create a 30-mL proximal gastric pouch. The band is connected to a subcutaneous access port through a narrow tube. After surgery, a series of stepwise adjustments to constrict the band stoma are made in the outpatient office. The gold standard technique in bariatric surgery is Roux-en-Y gastric bypass (RYGB) (Fig. 2).This is a proximal gastric bypass (using a 100- to 150-cm Roux-en-Y or alimentary limb is the norm in the United States). A small 30- to 50-mL proximal gastric pouch is created by dividing it from the larger stomach using staplers. The gastric pouch is then connected to the proximal jejunum (gastrojejunal anastomosis) in a Roux-en-Y fashion, using a variety of equally effective laparoscopic anastomotic techniques. Then, the biliopancreatic limb is reconnected to the jejunum (jejunojejunal anastomosis) ~100 to 150 cm from the gastrojejunostomy. Another technique is sleeve gastrectomy (SG) (Fig. 3) in which a left lateral portion of the gastric antrum (~5 cm from the pylorus), body, and fundus is separated from the medial portion using sequential stapler firings over a 36- to 46-Fr bougie. The "larger excess stomach" is removed from the abdominal cavity, leaving the smaller, left curvature-based, narrow stomach, preserving the pylorus and usual connection with the duodenum. Still another technique is biliopancreatic diversion without (BPD) or with duodenal-switch (BPD-DS) ([Fig. 4]). With this technique, a partial gastrectomy (BPD) or sleeve gastrectomy (BPD-DS) is created, and the small bowel is divided in two sections of similar length (alimentary and biliopancreatic limb).The alimentary limb is connected to the first portion of the duodenum (BPD-DS) or the stomach (BPD). The biliopancreatic limb is anastomosed to the distal small intestine ~50 to 100 cm proximal the ileocecal. Vertical banded gastroplasty (VBG) is an older technique that combines stomach stapling and gastric banding, which is not adjustable, to create a small gastric pouch. After an incision into the stomach is made, the sides of the incision are stapled, creating a hole in the stomach for the band to loop through. Above the created hole, the stomach is stapled.
(Enlarge Image)
Figure 1.
Adjustable gastric banding. Copyright © 2009 Covidien. All rights reserved. Used with the Permission of Covidien.
(Enlarge Image)
Figure 2.
Roux-en-Y gastric bypass. Copyright © 2009 Covidien. All rights reserved. Used with the Permission of Covidien.
(Enlarge Image)
Figure 3.
Sleeve gastrectomy. Copyright © 2009 Covidien. All rights reserved. Used with the Permission of Covidien.
(Enlarge Image)
Figure 4.
Biliopancreatic diversion with duodenal-switch (BPD-DS). Copyright © 2009 Covidien. All rights reserved. Used with the Permission of Covidien.
Many reports have been published about the safety of bariatric surgery, notably the report from the Longitudinal Assessment of Bariatric Surgery (LABS) Consortium and a systematic review of 14 comparative studies of RYGB and AGB. In the LABS study, where only major adverse outcomes were reported (death; venous thromboembolism; percutaneous, endoscopic, or operative re-intervention; and failure to be discharged from the hospital), the RYGB patients had higher BMI and more comorbidities than did the AGB patients. The complication and mortality rates were very low for all groups studied; it was higher for laparoscopic RYGB (4.8% and 0.2%, respectively) than for AGB (1% and 0%, respectively). In the systematic review, the rate of complications varied widely across these studies, likely also related to differences in patient baseline characteristics and in the definitions of adverse events and how they were identified. The types of complications differ between the procedures, and while RYGB and BPD-DS are considered by most experts to be more complex, many have demonstrated that, when done on properly selected and prepared patients, by properly trained surgeons at high-volume medical centers, all offer a low complication rate that is possibly similar to that for AGB, if the long-term complications (>30 days) with AGB are accounted. This is because RYGB and BPD-DS have more perioperative (<30 days) complications than AGB; however, AGB has a higher primary failure rate in providing appropriate weight loss, and more complications and reoperations after 30 days. One single center study from Belgium, with more than 12 years follow-up for patients that received AGB, showed that nearly 50% of the patients required removal of the AGB (with a total reoperation rate of 60%). In short, the LABS study only presented 30-day complication rates; thus, the high rates of reoperations reported by us and many others that are needed for the high failure and device-related problems rate observed after AGB are not yet accounted for. We look forward to the publication of the long-term results of the LABS Consortium. In addition, the differences in rare events such as mortality, reported by the LABS Consortium and others for RYGB and AGB may not be directly comparable, as there are significant differences between groups with respect to patient baseline characteristics; selection bias and confounding by severity also likely impacted these results.
Weight loss and the expected rate of resolution or improvement of T2DM are important outcomes when a patient chooses to have bariatric surgery. One remarkable and durable effect of bariatric surgery is a remission rate of T2DM reported in patients undergoing RYGB and BPD-DS for morbid obesity. Data from our studies and others demonstrate that T2DM improves or remits completely in as many as 80% of morbidly obese patients after RYGB and BPD-DS; this effect remains for several years in ~50% of patients. A recent systematic review and meta-analysis including 135,246 patients showed that excess weight loss and T2DM resolution in the first 12 months after surgery were higher for patients undergoing BPD-DS and RYGB (64% and 60% excess weight loss; 95% and 80% T2DM resolution; respectively), than for those undergoing AGB (46% excess weight loss, 57% T2DM resolution). Although follow-up data was incomplete in more than 40% of patients in the studies included in the analysis was a problem, the results are similar to those from series with more complete follow-up that demonstrate better weight loss and higher rates of T2DM resolution for RYGB and BPD-DS compared with AGB.
Indications, Techniques, Safety, and Outcomes for Bariatric Surgery
Currently, bariatric surgery is accepted as a treatment for obesity based on a combination of BMI levels and the presence of features of the metabolic syndrome. All techniques for performing bariatric surgery may be used in subjects with BMI ≥ 35 kg/m and any feature of the metabolic syndrome, or in subjects with BMI ≥ 40 kg/m independent of the presence of associated diseases. Recently, the U.S. Food and Drug Administration (FDA) approved the use of laparoscopic adjustable gastric banding for use in individuals with a BMI ≥ 30 kg/m and a feature of the metabolic syndrome. Nevertheless, bariatric surgery is not an option for every severely obese individual. Appropriate candidates are those who are willing to make significant changes in eating habits and lifestyle, and adhere to long-term follow-up care.
A few different bariatric surgery techniques are available and the choice of technique is currently based mainly on patient and surgeon preference, while taking into account the available evidence regarding the risks and benefits of each procedure. All techniques can be done using the laparoscopic approach. One of the most common and standard techniques available is adjustable gastric banding (AGB) (Fig. 1), in which an inflatable and adjustable silicone band is placed around the upper stomach, close to the gastroesophageal junction, to create a 30-mL proximal gastric pouch. The band is connected to a subcutaneous access port through a narrow tube. After surgery, a series of stepwise adjustments to constrict the band stoma are made in the outpatient office. The gold standard technique in bariatric surgery is Roux-en-Y gastric bypass (RYGB) (Fig. 2).This is a proximal gastric bypass (using a 100- to 150-cm Roux-en-Y or alimentary limb is the norm in the United States). A small 30- to 50-mL proximal gastric pouch is created by dividing it from the larger stomach using staplers. The gastric pouch is then connected to the proximal jejunum (gastrojejunal anastomosis) in a Roux-en-Y fashion, using a variety of equally effective laparoscopic anastomotic techniques. Then, the biliopancreatic limb is reconnected to the jejunum (jejunojejunal anastomosis) ~100 to 150 cm from the gastrojejunostomy. Another technique is sleeve gastrectomy (SG) (Fig. 3) in which a left lateral portion of the gastric antrum (~5 cm from the pylorus), body, and fundus is separated from the medial portion using sequential stapler firings over a 36- to 46-Fr bougie. The "larger excess stomach" is removed from the abdominal cavity, leaving the smaller, left curvature-based, narrow stomach, preserving the pylorus and usual connection with the duodenum. Still another technique is biliopancreatic diversion without (BPD) or with duodenal-switch (BPD-DS) ([Fig. 4]). With this technique, a partial gastrectomy (BPD) or sleeve gastrectomy (BPD-DS) is created, and the small bowel is divided in two sections of similar length (alimentary and biliopancreatic limb).The alimentary limb is connected to the first portion of the duodenum (BPD-DS) or the stomach (BPD). The biliopancreatic limb is anastomosed to the distal small intestine ~50 to 100 cm proximal the ileocecal. Vertical banded gastroplasty (VBG) is an older technique that combines stomach stapling and gastric banding, which is not adjustable, to create a small gastric pouch. After an incision into the stomach is made, the sides of the incision are stapled, creating a hole in the stomach for the band to loop through. Above the created hole, the stomach is stapled.
(Enlarge Image)
Figure 1.
Adjustable gastric banding. Copyright © 2009 Covidien. All rights reserved. Used with the Permission of Covidien.
(Enlarge Image)
Figure 2.
Roux-en-Y gastric bypass. Copyright © 2009 Covidien. All rights reserved. Used with the Permission of Covidien.
(Enlarge Image)
Figure 3.
Sleeve gastrectomy. Copyright © 2009 Covidien. All rights reserved. Used with the Permission of Covidien.
(Enlarge Image)
Figure 4.
Biliopancreatic diversion with duodenal-switch (BPD-DS). Copyright © 2009 Covidien. All rights reserved. Used with the Permission of Covidien.
Many reports have been published about the safety of bariatric surgery, notably the report from the Longitudinal Assessment of Bariatric Surgery (LABS) Consortium and a systematic review of 14 comparative studies of RYGB and AGB. In the LABS study, where only major adverse outcomes were reported (death; venous thromboembolism; percutaneous, endoscopic, or operative re-intervention; and failure to be discharged from the hospital), the RYGB patients had higher BMI and more comorbidities than did the AGB patients. The complication and mortality rates were very low for all groups studied; it was higher for laparoscopic RYGB (4.8% and 0.2%, respectively) than for AGB (1% and 0%, respectively). In the systematic review, the rate of complications varied widely across these studies, likely also related to differences in patient baseline characteristics and in the definitions of adverse events and how they were identified. The types of complications differ between the procedures, and while RYGB and BPD-DS are considered by most experts to be more complex, many have demonstrated that, when done on properly selected and prepared patients, by properly trained surgeons at high-volume medical centers, all offer a low complication rate that is possibly similar to that for AGB, if the long-term complications (>30 days) with AGB are accounted. This is because RYGB and BPD-DS have more perioperative (<30 days) complications than AGB; however, AGB has a higher primary failure rate in providing appropriate weight loss, and more complications and reoperations after 30 days. One single center study from Belgium, with more than 12 years follow-up for patients that received AGB, showed that nearly 50% of the patients required removal of the AGB (with a total reoperation rate of 60%). In short, the LABS study only presented 30-day complication rates; thus, the high rates of reoperations reported by us and many others that are needed for the high failure and device-related problems rate observed after AGB are not yet accounted for. We look forward to the publication of the long-term results of the LABS Consortium. In addition, the differences in rare events such as mortality, reported by the LABS Consortium and others for RYGB and AGB may not be directly comparable, as there are significant differences between groups with respect to patient baseline characteristics; selection bias and confounding by severity also likely impacted these results.
Weight loss and the expected rate of resolution or improvement of T2DM are important outcomes when a patient chooses to have bariatric surgery. One remarkable and durable effect of bariatric surgery is a remission rate of T2DM reported in patients undergoing RYGB and BPD-DS for morbid obesity. Data from our studies and others demonstrate that T2DM improves or remits completely in as many as 80% of morbidly obese patients after RYGB and BPD-DS; this effect remains for several years in ~50% of patients. A recent systematic review and meta-analysis including 135,246 patients showed that excess weight loss and T2DM resolution in the first 12 months after surgery were higher for patients undergoing BPD-DS and RYGB (64% and 60% excess weight loss; 95% and 80% T2DM resolution; respectively), than for those undergoing AGB (46% excess weight loss, 57% T2DM resolution). Although follow-up data was incomplete in more than 40% of patients in the studies included in the analysis was a problem, the results are similar to those from series with more complete follow-up that demonstrate better weight loss and higher rates of T2DM resolution for RYGB and BPD-DS compared with AGB.
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